Method of making a valve with adjustable valve seat

ABSTRACT

A direct solenoid operated poppet valve having an adjustable valve seat that provides a selectively variable flow orifice for supplying a preset air flow requirement. The poppet valve spool stroke is set in accordance with the preset air flow requirement. Then, based on the measured poppet location with respect to the solenoid pole piece, a solenoid push pin is selected that provides the minimum solenoid stroke required for the preset valve stroke and preset air flow requirement.

This is a division of application Ser. No. 07/670,889 filed on Mar. 18,1991 now U.S. Pat. No. 5,092,365.

BACKGROUND OF THE INVENTION

1. Technical Field

The field of art to which this invention pertains may be generallylocated in the class of devices relating to valves. Class 137, FluidHandling, U.S. Patent Office Classification, appears to be theapplicable general area of art to which the subject matter similar tothis invention has been classified in the past.

2. Background Information

This invention relates to direct solenoid operated poppet valves, suchas three-way and four-way directional flow control poppet air valveshaving an adjustable valve seat that provides a variable flow orificefor supplying a preset air flow requirement, with minimum valve andsolenoid strokes and maximum air flow control efficiency.

At the present time, industry is requiring smaller and more efficientvalves. One of the problems that must be overcome to meet therequirement of smaller and more efficient directional flow controlpoppet air valves is the reduction of the manufacturing toleranceaccumulation between the moving parts of a valve and the parts of thesolenoid for operating the valve. The tolerances in a direct solenoidoperated poppet air valves of this type are due to poppet and poppetseat locations in the valve body, and push pin and pole piece tolerancesin the solenoid.

It is an object of the invention to provide a direct solenoid operatedpoppet air valve having an adjustable valve seat that provides avariable air flow orifice which permits the valve stroke to be setaccurately in accordance with a selected air flow requirement, with aresultant accurate minimum solenoid stroke based on the valve stroke.

It is another object of the invention to provide a method of reducingthe manufacturing tolerance accumulation in a direct solenoid operatedpoppet air valve, so as to selectively provide a poppet air valve with alow air flow requirement and low power solenoid, or with a high air flowrequirement and a high power solenoid.

It is a further object of the invention to provide a direct solenoidoperated poppet air valve wherein the valve stroke is set, then based onmeasured poppet location with respect to the solenoid pole piece, a pushpin is selected that will provide the minimum solenoid stroke requiredfor the preset valve stroke.

It is still another object of the invention to provide a direct solenoidoperated poppet air valve having an adjustable valve seat, and whereinthe solenoid is provided with a pole piece. operated poppet air valve ofthe invention provides a directional flow control poppet air valve withflow control efficiency, a short stroke, and a minimum power solenoid,so as to provide directional flow control air operations with a minimumof energy used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a horizontal section view of a direct solenoid operatedthree-way directional flow control poppet air valve provided with athreaded adjustable poppet valve seat, and with the solenoid shown withparts broken away and parts in section.

FIG. 2 is a horizontal section view of a direct solenoid operatedfour-way directional flow control poppet air valve provided with athreaded adjustable poppet valve seat, and with the solenoid being shownin a fragmentary, section view.

FIG. 3 is an end view of the right end poppet valve seat retainer shownin FIG. 2, taken along the line 3--3 thereof, and looking in thedirection of the arrows.

FIG. 4 is a fragmentary, right end section view of the four-waydirectional flow control poppet air valve showing the hand tool, usedfor adjusting the threaded adjustable poppet valve seat for the centralpoppet valve element.

FIG. 5 is an elevation view of the left end of the valve seat adjustingtool shown in FIG. 4.

FIG. 6 is a rear elevation view of the threaded

SUMMARY OF THE INVENTION

The aforegoing objects are accomplished by providing a direct solenoidoperated poppet air valve, which has a poppet air valve member carryinga poppet valve element having an angled poppet valve face on each end.The poppet valve element is movably disposed in a valve body between afixed poppet valve seat and an adjustable poppet valve seat foralternate seating engagement with said angled poppet valve faces. Thepoppet valve member is moved axially in one direction by a return springto a position where one of the angled poppet valve faces seats on thefixed poppet valve seat. A flow of air under pressure is put through theflow orifice between the other angled poppet valve face and theadjustable poppet valve seat. The adjustable poppet valve seat is movedtoward the other angled poppet valve face on the poppet valve elementuntil the flow of air through said flow orifice reaches a certain airflow requirement.

The poppet valve member is moved in the other direction to seat saidother angled poppet valve face on the adjustable poppet valve seat by adirectly engagable solenoid. All of the tolerances for manufacturing thepoppet valve member, the axial bore in the valve body for the poppetvalve member, are controlled from the end of the valve body againstwhich the solenoid is seated. Also, the tolerances for the parts of thesolenoid, namely the length of the pole piece, is determined with aminimum of tolerance accumulation from said end of the valve body. Thedirect solenoid adjustable poppet valve seat structure shown in FIGS. 2and 4.

FIG. 7 is a top view of the threaded adjustable poppet valve seat shownin FIG. 6, taken in the direction of the arrow "7".

FIG. 8 is a horizontal section view of the threaded adjustable poppetvalve seat shown in FIG. 6, taken along the line 8--8 thereof, andlooking in the direction of the arrows.

FIG. 9 is a fragmentary view, similar to the valve structure shown inFIG. 4, but with the adjustable poppet valve seat being mounted in placeby a press fit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, and in particular to FIG. 1, the numeral 10generally designates a direct solenoid operated three-way directionalflow control poppet air valve which includes a valve body, generallyindicated by the numeral 11, and a solenoid actuator, generallyindicated by the numeral 12. The poppet air valve 10 may be used byitself or adapted to be operatively mounted on an air flow control valveto control, as for example, a four-way valve, a three-way valve, atwo-way valve, and the like. The valve body 11 is provided with a pairof mounting holes 13 for the reception of suitable mounting bolts tomount the solenoid operated poppet air valve 10 in an operativeposition.

The valve body 11 is provided with an air inlet port 14 whichcommunicates with an annular groove 15 that is formed in the wall of anaxial bore 16 that is formed in the valve body 11, perpendicular to thelongitudinal axis of the inlet port 14.

As shown in FIG. 1, a valve retainer, generally indicated by the numeral20, is seated in a stepped axial bore in the valve body 11. The steppedaxial bore for the valve retainer 20 comprises an outer threaded portion21 which is open to the outer or right end of the valve body 11, asviewed in FIG. 1, and a reduced diameter inner end smooth bore portion22 which communicates at its inner end with the axial bore 16. The innerend of the reduced diameter bore portion 22 terminates at a transverseshoulder 23, at which point the inner end of the bore portion 22communicates with the inner end of the axial bore 16 to form a circular,sharp edged poppet valve seat 24. The inner end of the reduced diameterbore portion 22 communicates with a cylinder or supply port 25.

As shown in FIG. 1, the inner end 26 of the valve retainer 20 iscylindrically formed and is slidably mounted in the retainer boreportion 22. An axial bore 28 is formed in the valve retainer 20, and itextends rearwardly from the inner end of the valve retainer 20 andterminates at an end wall 29. An O-ring seal 30 is operatively mountedaround the outer periphery of the inner end 26 of the valve retainer 20and it slidably engages the surface of the bore portion 22. The outer orrear end of the valve retainer 20 is enlarged, and is provided with athreaded periphery that is threadably mounted in the threaded outer boreportion 21 which communicates with the reduced diameter inner boreportion 22. The valve retainer 20 is provided on the outer end thereofwith a transverse slot 31 for the reception of a tool such as a screwdriver, for turning the valve retainer 20 to a desired location in thestepped diameter axial bore portions 21, 22.

An exhaust port 35 is formed in the valve body 11 adjacent the right endthereof, as viewed in FIG. 1. The exhaust port 35 communicates with theaxial bore 16, through an annular groove 36 formed in the periphery ofthe rear end of the stepped diameter axial bore portion 22 and aplurality of aligned radial passageways 37, which are formed through theside wall of the valve retainer 20. A short axial bore 38 is formed inthe inner end of the valve retainer 20, and it is made to a diameterlarger then the diameter of the bore 28 in the valve retainer 20. Thebore 38 terminates at a shoulder 39 to form a sharp edged poppet valveseat 40 at the junction point with the axial bore 28 in the valveretainer 20.

A poppet valve member or spool, generally indicated by the numeral 43,is movably mounted in the valve body 11, with the outer end 44 thereofdisposed in the valve retainer bore 28 and the inner end thereofdisposed in the valve body axial bore 16. The poppet valve spool 43 isprovided with an elongated, substantially cylindrical body, which hasthe outer end 44 slidably mounted in the axial bore 28 of the valveretainer 20. The poppet valve spool outer end 44 is seated against avalve spool return spring 45 which has an inner end seated in an axialbore 46 in the poppet valve spool outer end 44. The outer end of thereturn spring 45 is seated against the end wall 29 formed at the outerend of the axial bore 28 in the valve retainer 20. The outer end 44 ofthe poppet valve spool 43 has operatively mounted therearound an O-ringseal 47 which is mounted in a suitable groove formed in the periphery ofthe bore 28 in the valve retainer 20. The inner end of the poppet valvespool 43 has operatively mounted therearound an O-ring seal 48, which isseated in a groove formed in the wall of the axial bore 16 in the valvebody 11.

As shown in FIG. 1, the poppet valve spool 43 is provided with acentrally located, annular flange 50 which is conically shaped and hasangled outer end faces which converge toward each other, and on whichare integrally molded from a suitable elastomeric material, a pair ofangled poppet valve faces 51 and 52.

As shown in FIG. 1, the solenoid 12 includes a pole piece 54 which seatsdirectly on the adjacent end surface 55 of the valve body 11. The polepiece 54 has an axial bore 56 formed therethrough which communicates atthe outer end thereof with the valve spool axial bore 16. Slidablymounted in the axial bore 56 is a cylindrical valve push pin 57. One end58 of the valve push pin 57 is seated against the inner end 59 of thepoppet valve spool 43. The other end 60 of the valve push pin 57 isseated against the adjacent end 61 of the solenoid armature 62. It willbe understood, that the solenoid 12 includes the usual coil and otherconventional parts of a solenoid for moving the solenoid armature 62 tothe right, as viewed in FIG. 1, to move the valve push pin 57, and inturn to move the poppet valve spool 43, to the right when the solenoid12 is energized. The solenoid 12 may be a DC or an AC solenoid. Thenumeral 63 designates the length of the stroke of the solenoid armature62 when the solenoid 12 is de-energized. The numeral 64 designates thelength of the stroke of the poppet valve spool 43 before it is movedfrom its normal inoperative position shown in FIG. 1 to a positionwherein the angled poppet valve face 52 seats on the sharp edged poppetvalve seat 40.

The end surface 55 of the valve body 11 functions as a control surfacefrom which the dimensions of the hereinafter discussed parts of thevalve 10 and solenoid 12 are measured and controlled with minimumtolerances. The end surface 55 of the valve body 11 is accuratelymachined to receive the outer end 67 of the pole piece 54. The length ofthe pole piece 54 is accurately determined, and the inner end 68 of thepole piece 54 is machined to control the length of the pole piecebetween its end s 67 and 68, with a minimum tolerance. The length of thevalve body portion between the valve body end surface 55 and the fixedsharp edged poppet valve seat 24 is determined and machined with aminimum tolerance. The dimensional length of the poppet valve spool 43between its inner end surface 59 and the poppet valve seat contact pointon the angled poppet valve face 51, where it seats on the fixed sharpedged poppet valve seat 24 is determined and machined with a minimumtolerance. The length between the seating points on the angled poppetvalve faces 51 and 52 is determined and machined with a minimumtolerance.

In accordance with the invention, a predetermined flow of air throughthe variable orifice formed by the space between the sharp edged poppetvalve seat 40 and the angled poppet valve face 52 may be varied toprovide a selected preset flow of air therethrough, by adjusting theposition of the sharp edged poppet valve seat 40 axially inward oroutward. With the poppet valve spool 43 in the position shown in FIG. 1,the port 35, which is normally an exhaust port, would be connected to asource of air under pressure, and the flow of air through theaforementioned variable flow orifice would be measured as the air flowsout through the cylinder port 25. The valve retainer 20 would beadjusted inwardly or outwardly, as necessary to set the sharp edgedpoppet valve seat 40 to a position to permit the selected flow of airthrough the valve 10. When the adjustable sharp edged poppet valve seat40 is in the position to give the selected air flow through the valve10, the valve stroke length 64 of the poppet valve spool 43 isdetermined and measured, as illustrated in FIG. 1. The dimension betweenthe inner end surface 59 of the poppet valve spool 43 and the outer end68 of the pole piece 54 is measured, and from a supply of machined pushpins of various lengths, a push pin 57 is selected which has a length toprovide the required solenoid stroke length 63 of the solenoid armature62, to actuate the poppet valve spool 43, through a precise axialmovement, to move the poppet valve spool 43, as viewed in FIG. 1,through a stroke 64 to seat the angled poppet valve face 52 on theadjustable sharp edged poppet valve seat 40. It will be seen, that byproviding the adjustable sharp edged poppet valve seat 40 and making theaforedescribed parts of the valve 72 and solenoid 12 to the describedcontrolled lengths, that a poppet valve is provided with a preset strokeeliminating all of the tolerances associated with the mass production ofcomponent parts used in the assembly of the valve. The adjustable sharpedged poppet valve seat 40 may be adjusted to vary the air flow throughthe orifice between the sharp edged poppet valve seat 40 and the angledpoppet valve face 52 to obtain the desired poppet stroke for the poppetvalve 10.

It will be seen, that by holding the tolerances close in machining theaforementioned parts of the valve 72 and the solenoid 12, the movingparts of the valve 72 and the solenoid 12 can be made and assembled withan overall minimum tolerance for said parts. After a poppet stroke isset by adjusting the seat 40, the dimension 65 from the inner end 59 ofthe poppet valve spool 43 to the inner end 68 of the pole piece 54 ismeasured, and a push pin 57 is selected from an inventory of push pinsto provide a solenoid stroke 63 sufficient to move the poppet valvespool 43 through the required valve stroke 64. The solenoid stroke 63 ismade to a length longer than the valve stroke 64 by an amount sufficientto account for the slight compression of the angled poppet valve face 52when it seats on the sharp edged valve seat 40. In one three-way valve10 made in accordance with the invention, the valve stroke 64 was 0.13millimeters in length and the solenoid stroke was set at 0.20millimeters.

In use, with the poppet valve spool 43 in the initial position shown inFIG. 1, pressurized air entering the inlet port 14 is blocked from thesupply port 25 and the exhaust port 35, and the supply port 25 is incommunication with the exhaust port 35. When the solenoid 12 isenergized the poppet valve spool 43 is moved to the right, to open theflow path between the inlet port 14 and the supply port 25, and to blockcommunication between the supply port 25 and the exhaust port 35. Thedetails of the operation of a three-way valve as illustrated in FIG. 1,is described more fully in U.S. Pat. Nos. 4,298,027 and 4,829,275, andthe description of the operation of such three-way valves described indetail therein is incorporated herein by reference.

FIG. 2 illustrates the application of the principles of the invention toa direct solenoid operated four-way directional flow control poppet airvalve, generally designated by the numeral 72, which includes a valvebody generally designated by the numeral 73. A solenoid actuator isshown in fragment, and in section, and the reference numeralsdesignating the solenoid parts shown are the same reference numerals asused in FIG. 1 for the solenoid 12, followed by small letter "a".

As shown in FIG. 2, the valve 72 is provided with a pair of mountingbolt holes 74 which extend through the valve body 73 and are adapted toreceive suitable mounting bolts for securing the valve 72 in anoperating position on an apparatus with which it is to be employed.

As shown in FIG. 2, the valve body 73 is provided with a threaded inletport 75, which is adapted to be connected to a suitable source ofpressurized air. The inlet port 75 communicates with an axial valvespool bore 76 in the valve body 73. The axial valve spool bore 76 iscentered longitudinally in the valve body 73, and it communicates on theleft side thereof, as viewed in FIG. 2, with an enlarged diameter axialbore 77 that has a further enlarged diameter threaded outer end bore 78which is open at the left end of the valve body 73, as viewed in FIG. 2.The left end surface 79 of the valve body 73 is a control surface, andfunctions in the same manner as the valve body control surface end 55 inthe first embodiment of the invention illustrated in FIG. 1. The rightend of the axial valve spool bore 76, as viewed in FIG. 2, communicateswith an enlarged diameter axial bore 80 which is of the same diameter asthe axial bore 77. The enlarged diameter axial bore 80 extends to theright end of the valve body 73 and terminates in a further enlargeddiameter threaded end bore 81. The valve 72 is provided with a pair ofcylinder ports 82 and 83 which communicate with the enlarged axial bores77 and 80, respectively.

A fixed sharp edged poppet valve seat 86 is formed in the valve body 73,at the transverse junction point between the axial valve spool bore 76and a transverse passage 87 which communicates the inlet port 75 withthe axial valve spool bore 76.

As shown in FIG. 2, an adjustable sharp edged poppet valve seat,generally designated by the numeral 88, is disposed to the right of thepassage 87, and in a position spaced apart, but axially aligned with thefixed sharp edged poppet valve seat 86. The adjustable sharp edgedpoppet valve seat 88 is formed in a threadably mounted adjustable body,generally indicated by the numeral 89, which is cylindrical in shape andprovided with a threaded outer periphery 90, as shown in more detail inFIGS. 6, 7 and 8. As shown in FIG. 2, the adjustable sharp edged poppetvalve seat body 89 is threadably mounted in the reduced diameter,threaded inner end 91 of the axial bore 80.

As best seen in FIG. 8, the adjustable sharp edged poppet valve seatbody 89 has formed therethrough a stepped diameter bore, including acentral bore 92 which communicates at its front end with an enlargedbore 93 and at its rear end with an enlarged bore 94. It will be seen,that the junction point between the central bore 92 and the largerdiameter front end bore 93 forms the adjustable sharp edged poppet valveseat 88. The adjustable sharp edged poppet valve seat body 89 isprovided on the rear end thereof, with a pair of transverse slots 95which are adapted to receive the end of an adjusting tool 142 foradjusting the adjustable sharp edged poppet valve seat body 89 in thethreaded bore 91 (FIG. 2) in the valve body 73.

As shown in FIG. 2, the flow of pressurized air from the inlet port 75and through the valve body 73 is controlled by a longitudinally movablepoppet valve spool, generally indicated by the numeral 98. The poppetvalve spool 98 comprises an elongated cylindrical body which includes acentral portion 99, and two integral end portions 100 and 101. Thepoppet valve spool 98 is provided with a centrally located, annularradial flange 104 which is conically shaped and has angled outer endfaces that converge toward each other, and on which are integrallymolded, from a suitable elastomeric material, a pair of angled poppetvalve faces 105 and 106.

As shown in FIG. 2, the enlarged left end 100 of the poppet valve spool98 is slidably mounted in an axial bore 107 which is formed through aleft end bushing 108 that is threaded on the outer periphery thereof,and threadably mounted in the threaded bore 78 in the valve body 73. Theenlarged diameter right end 101 of the poppet valve spool 98 is slidablymounted in an axial bore 109 which is formed in a right end bushing 110that is provided with a threaded outer periphery which is threadablymounted in the threaded bore 81 in the valve body 73. The enlarged rightend 101 of the poppet valve spool 98 is seated against a valve spoolreturn spring 114 which has an inner end seated in an axial bore 115formed in the right end 101 of the poppet valve spool 98. The outer endof the return spring 114 is seated against the inner side of the bushingend wall 113.

As shown in FIG. 2, the poppet valve spool 98 is provided with a leftend poppet valve element 118 which is molded around the outer peripheryof the poppet valve spool 98, at the junction point between the left endof the central portion 99 and the left end enlarged portion 100 of thepoppet valve spool 98. A similar right end poppet valve element 119 ispositioned at the junction point between the poppet valve spool centralportion 99 and the right end enlarged portion 101. The left and rightend bushings 108 and 110 are cylindrical, and they each have acylindrical inner end reduced diameter portion 120 and 121,respectively, which are slidably mounted in the axial bores 77 and 80,respectively. A suitable O-ring 122 is operatively mounted in a grooveformed around the outer periphery of the left bushing inner end 120. Asimilar O-ring 122 is operatively mounted in a groove formed around theperiphery of the inner end 121 of the right end bushing 110. As shown inFIG. 2, a conically angled poppet valve seat 123 is formed on the leftend bushing inner end 120, and an identical conically angled poppetvalve seat 124 is formed on the right end bushing inner end 121.

As shown in FIG. 2, the valve body 73 has formed therein a first exhaustport 128 which communicates with the cylinder port 82 through a steppeddiameter passage 129 formed through the left end bushing 108, a bore 130through the inner end of the left end bushing 108 and the bore 77. Asecond exhaust port 131 in the valve body 73 communicates with thecylinder port 83 through a stepped passage 132 formed through the innerend of the right end bushing 110, an axial bore 133 formed through theright end bushing inner end 121, and the axial bore 80.

As shown in FIGS. 2 and 3, the outer ends of the bushings 108 and 110are provided with spaced apart, transverse wrench surfaces 134, for theacceptance of a suitable wrench for threadably rotating the end bushings108 and 110 to a desired adjusted position.

The solenoid 12a for the four-way valve 72 is structurally andfunctionally the same as described hereinbefore, for the solenoid 12employed in the first embodiment of FIG. 1. The push pin 57a seatsagainst the left end 136 of the poppet valve spool 98.

In use, with the poppet valve spool 98 in the initial or first positionshown in FIG. 2, and with the solenoid 12a de-energized, whenpressurized air is admitted into the inlet port 75 it will flow past theopen valve seat 88 and into the valve bore 80, and out through thecylinder port 83 to the air cylinder or other apparatus being operatedby the valve 72. Simultaneously, air from said air cylinder or otherapparatus is exhausted into the cylinder port 82 and it flows throughthe axial bore 77 and past the open poppet valve seat 123, and throughthe stepped passage 129 and out of the valve 72 through the exhaust port128.

When the solenoid 12a is energized the poppet valve spool 98 is moved tothe right, to a second operating position, wherein the angled poppetvalve face 105 seats on the poppet valve seat 88, and the left endpoppet valve element 118 seats on the poppet valve seat 123. Inletpressurized air then flows from the inlet port 75, and past the valveseat 86 and into the axial bore 77, and into the cylinder port 82, andthence to the air cylinder or other apparatus being controlled.Simultaneously, air from said air cylinder or other apparatus beingcontrolled enters the port 83 and passes into the axial bore 80 andthrough the axial bore 133 in the right end bushing inner end 121 andout through the stepped passage 132 and out of the valve 72 through theexhaust port 131.

Details of the operation of a substantially similar four-way valve asillustrated in FIG. 2, is described more fully in U.S. Pat. No.4,574,844, and a description of the operation of such four-way valvedescribed in detail in said patent is incorporated herein by reference.

The numeral 137, in FIG. 2 designates the length of the stroke of thesolenoid armature 62a when the solenoid 12a is de-energized. The numeral138 designates the length of stroke of the poppet valve spool 98 beforeit is moved to the right from its initial operative position shown inFIG. 1, to a second operative position wherein the angled poppet valveface 105 seats on the sharp edged poppet valve seat 88.

The left end surface 79 of the valve body 73 functions as a controlsurface from which the dimensions of the hereinafter discussed parts ofthe valve 72 and the solenoid 12 are measured and controlled withminimum tolerance. The valve body end surface 79 is accurately machinedto receive the outer end surface 67a of the solenoid pole piece 54a. Thelength of the pole piece 54a is determined, and the inner end 68a of thepole piece 54a is machined to control the length of the pole piece 54abetween its ends 67a and 68a with a minimum tolerance. The length of theportion of the valve body 73, between the valve body control end surface79 and the fixed sharp edged poppet valve seat 86, is determined andmachined with a minimum tolerance. The dimensional length of the poppetvalve spool 98, between its left end surface 136 and the poppet valveseat contact point on the angled poppet valve face 106, where it seatson the fixed sharp edged poppet valve seat 86 is determined, and thelength between the seating points on the angled poppet valve faces 105and 106 is determined.

In accordance with the invention, the adjustable sharp edged poppetvalve seat body 89 may be threadably adjusted in the threaded bore 91 topreset the sharp edged poppet valve seat 88 in a position to provide apreset flow of air through the orifice between the sharp edged poppetvalve seat 88 and the angled poppet valve face 105 by the followingdescribed procedure. The valve body 73 is installed in an appropriateassembly fixture with all valve parts in place except the right endbushing 110. The adjustable poppet valve seat body 89 is installed overthe spring end 101 of the poppet valve spool 98, with the drive slots 95facing outward. The poppet valve spool 98 is installed in the valve body73 at a position where the angular poppet face 106 contacts the fixedpoppet seat 86. The spring 114 is installed in the spring pocket 115.The seat adjusting tool 142 is then inserted over the poppet valve spool98 until the drive fingers 145 engage the drive slots 95 on theadjustable poppet valve seat body 89.

As shown in FIG. 4, the valve seat adjusting tool 142 has an axial boreformed in the front end thereof, and it extends rearwardly andterminates at an end wall 147. An O-ring 146 is operatively mounted in agroove formed around the outer periphery of the cylindrical valve seatadjusting tool 142, and it sealingly engages the axial bore 80 to sealany flow of air out of the exhaust port 131. The front end of the valveseat adjusting tool 142 has an integral, reduced diameter front endportion 144, which is provided on its front outer end with a pair ofintegral, diametrically spaced apart drive fingers 145 that are adaptedto be seated in and mesh with the drive slots 95 formed in the rear endof the adjustable poppet valve seat body 89. It will be seen, that theadjustable valve seat body 89 may be adjusted forwardly or rearwardly byrotating the valve seat adjusting tool 142 in the appropriate directionin order to change the flow capacity through the variable orifice formedbetween the adjustable valve seat 88 and the angled poppet valve face105.

In carrying out the adjustment procedure to set the adjustable poppetvalve seat 88 to a desired position to provide a selected preset flow ofair thereby, the inlet port 75 is connected to a source of air underpressure and the flow of air through the variable flow orifice betweenthe adjustable poppet valve seat 88 and the angled poppet valve face 105passes into the axial bore 80 and out through the cylinder port 83, andit is measured, by any suitable flow meter as it flows out of thecylinder port 83. The adjustable valve seat body 89 is then adjusted bythe valve seat adjusting tool 142 until the selected preset flow of airexiting from the cylinder port 83 is obtained. The valve seat adjustingtool 142 is then replaced by the right end bushing 110.

In one four-way valve 72 made in accordance with the invention, thevalve stroke 138 was 0.13 millimeters in length for a preset flow of airand the solenoid stroke was set at 0.20 millimeters, for the selectedpreset flow of air to be passed through and, controlled by the valve 72.

FIG. 9 shows a fragmentary portion of the four-way valve illustrated inFIG. 2. The valve structure and valve seat adjusting tool 142 shown inFIG. 9 is the same as shown in FIG. 4, with the exception that theadjustable poppet valve seat body is indicated by the numeral 89b andthe outer periphery thereof is not threaded, but is provided with asmooth cylindrical surface. Also, the valve body threaded bore 91 isreplaced with a smooth cylindrical bore 91b, whereby the adjustablevalve seat body 89b is adapted to be mounted in the bore 91b with apress fit. The valve seat adjusting tool 142 is adapted to move theadjustable poppet valve seat body 89b axially inward, or to the left, asviewed in FIG. 9, to a position to give a selected preset flow of airthrough the valve.

The fixed sharp edged poppet valve seats 24 and 86 may also each betermed a stop means.

What is claimed is:
 1. A method of providing a solenoid operated poppetair valve (10)(72), with a minimum overall tolerance for the movingparts of the valve and the solenoid, and with a poppet valve spoolstroke based on a preset selected flow requirement, and a solenoidstroke based on the stroke of the poppet valve spool, and wherein thevalve has a valve body (11)(73) with a valve bore (16)(76) and a poppetvalve spool (43)(98) slidably mounted therein, and with a poppet valveelement (50)(104) on said poppet valve spool (43)(98) having axiallyspaced apart ends with an angled poppet valve face (51,52)(105,106) oneach end, and wherein a first poppet valve seat (24)(86) is fixedlyformed on said valve body (11)(73) in said valve bore (16)(76) adjacentone end of the poppet valve element (50)(104), and a second poppet valveseat (40)(88) is mounted in said valve bore (16)(76) in the valve body(11)(73) adjacent the other end of the poppet valve element (50)(104),and with a solenoid (12)(12a) having a pole piece (54)(54a), and whereinsaid poppet valve spool ((43)(98) is shiftable directly by the solenoid(12)(12a) in a short stroke, between a first position with the angledpoppet valve face (51)(106) on one end of the poppet valve element(50)(104) seated on the first poppet valve seat (24)(86) and the otherangled poppet valve face (52)(105) spaced apart from the second poppetvalve seat (40)(88) to provide a variable flow orifice therebetween, anda second position with the positions of the angled poppet valve facesreversed, comprising the steps of:(a) forming said second poppet valveseat as an adjustable poppet valve seat (40)(88); (b) providing one endof the valve body (11)(73) with a control end surface (55)(79) machinedwith a minimum tolerance; (c) machining the length of the valve bore(16) (76) from said valve body control end surface (55)(79) to the fixedpoppet valve seat (24)(86) with a minimum tolerance; (d) machining thelength of the poppet valve spool (43)(98) between the end surface(59)(136) thereof adjacent said valve body control end surface (55)(79)and the fixed poppet valve seat (24)(86) contact point on the angledpoppet valve face (51)(106) which seats on the fixed poppet valve seat(24)(86) with a minimum tolerance; (e) machining the axial length of thevalve element (50)(104) between the seating points on the angled poppetvalve faces (50,51)(105,106) with a minimum tolerance; (f) mounting oneend of the pole piece (54)(54a) for the solenoid (12)(12a) directly onthe control end surface (55)(79) of the valve body (11)(73); (g) sendinga flow of air through the valve body (11)(73) and through the orificebetween said other one of the angled poppet valve faces (52)(105) andthe adjacent adjustable poppet valve seat (40)(88), and measuring theflow of air through said orifice, and adjusting the position of theadjustable poppet valve seat (40)(88) until the selected flowrequirement is reached whereby the stroke (64)(138) of the poppet valvespool (43)(98) to seat the last mentioned angled poppet valve face(52)(105) on the adjustable poppet valve seat (40)(88) is set; (h)measuring the axial dimension (65)(139) between the end surface(59)(136) of the poppet valve spool (43)(98) which is adjacent the valvebody control end surface (55)(79) and the other end (68)(68a) of thepole piece (54)(54a); and, (i) selecting a push pin (57)(57a) of alength equal to the sum of the last mentioned measured axial dimension(65)(139) plus the length of the valve stroke (64) set by the measuredflow of air through said orifice, and the length of a selected solenoidstroke (63)(137).